1. Field of the Invention
The present invention relates to an intake/exhaust valve assembly for an internal combustion engine which is adapted to drive intake/exhaust valves provided to each power cylinder of an internal combustion engine, and more specifically to an intake/exhaust valve assembly which is capable of suspending the open and close operation of a part of intake and exhaust valves under a specific operational condition of the engine.
2. Description of the Prior Art
A type of internal combustion engine is known in which each of power cylinders is provided with a plurality of intake or exhaust valves, for example, 4 valves per cylinder or 6 valves per cylinder.
In order to maintain a sufficient efficiency of the valve operation when the engine is operating at high speed, and to eliminate the blow-by of the mixture due to a so called "overlap" of the valve timing when the engine is operating at medium or low speed, it is preferable to provide an internal combustion engine of the type described above with the function of suspending the operation of a part of intake or exhaust valves when the engine is operating at medium or low speed.
Such a type of intake/exhaust valve assembly is disclosed, for example, in Japanese Patent provisional publication No. 54-36415.
In the case of the prior art valve assembly, however, there were several drawbacks that the construction of the assembly tends to be excessibly complicated, and therefore the durability thereof was not enough.